The identification of acute HCV infection has been a major challenge throughout the years as its natural course is usually silent and asymptomatic. Collaborative efforts are being made throughout the worid to recognize new cases as they offer relevant information on viral and host interactions. This continued project has already identified 77 cases of acute HCV infection; most of which were symptomatic (80%), and with risk factors being mainly nosocomial in medical settings followed by sexual transmission. Spontaneous clearance was documented in 54%. and most cases were due to a single exposure as there were no reports of intravenous drug use. Even though patients were referred to hepatitis treatment centers as eariy as 3 months, a number of patients were not treated during the acute phase, and we were, surprisingly able to observe delayed spontaneous clearance in a few. Subjects adhered highly to the study and results have been obtained through a follow-up of pafients during a course of almost 9 years, with a high yield of sequenfial and serial bank specimens. This study will not only help identify HCV in the eariy phase of infecfion but also offer confinued long fime serial samples for further studies on immune pathogenesis for future development of successful immunotherapeutic intervenfions and vaccines.